JP4568772B2 - Fluid operated valve assembly - Google Patents

Description

(Technical field)
The present invention relates to a fluid operated valve assembly according to the preamble of claim 1.

  The invention further relates to the use of a fluid operated valve assembly for operating an EGR valve in a diesel engine vehicle.

(Background of the Invention)
The need for hydraulic or compressed air actuated actuators such as valve assemblies exists in many technical fields. In a conventional actuator, the piston is arranged for reciprocating movement in the cylinder, and the piston cooperating with the actuator rod is connected to a component whose relative position is variable. In a valve assembly, such a component is a valve closure member. In a typical example, the piston is provided with at least one piston ring to ensure that the working fluid does not leak beyond the piston. In many applications, the piston ring is made from a flexible elastic material such as a rubber or plastic material. However, in an operating environment where the actuator may be subjected to high temperatures, it is impossible to use a material having a low melting point. In such a case, conventionally, for example, it was necessary to employ a piston ring made of spring steel.

  However, even spring steel has limitations as to the temperature it can receive. For example, it is not possible to use such an actuator near the exhaust manifold of an internal combustion engine unless special care is taken.

Fluid operated actuator that employs a piston that does not require piston rings, the applicant's name, is described in Patent Document 1 (SE 9604287-4). In this document, the spring means maintains the piston in a first end position where the first region of the piston is in sealing engagement with the first valve seat of the piston housing. The air acts on the piston and overcomes the spring force of the spring means so that the piston is displaced to the second end position where the second valve seat and the second region of the piston are in the sealing engagement state in the housing. The actuator is actuated by passing air through the cylinder. In order for the piston to retake its first end position, air is discharged from the cylinder and the spring means pushes the piston into sealing engagement with the first valve seat.

When the actuator of Patent Document 1 is used to actuate a valve closing member, the valve closing member is connected to a piston via an actuator rod. To ensure that the valve closing member seal-engages its valve seat when the piston is in its second end position, the piston stroke cannot exactly correspond to the valve closing member stroke. Again, the actuator rod cooperates with the piston by a flexible connection. The flexible connection utilizes a helical spring and allows axial displacement of the actuator rod relative to the piston.

The actuator disclosed in U.S. Patent No. 6,057,031 provides significant advantages over conventional actuators, but its operation depends on the presence of spring means, and the sealing engagement of the valve closure member with its valve seat as well as the actuator Both return operations are also performed reliably.
No. 9604287-4 specification

( Summary of the Invention )
The object of the present invention is to provide a fluid operated valve assembly suitable for use in harsh environments, the operation of which does not depend on the spring means acting on the piston.

  This object is achieved by a valve assembly according to claim 1.

  Preferred embodiments of the valve assembly according to the invention are described in detail in the dependent claims.

  The invention further relates to the use of the claimed valve assembly in diesel engine vehicles, in particular as an exhaust gas recirculation valve.

More specifically, the present invention can relate to the following items.

  (Item 1) A fluid operated valve assembly (10) comprising a housing (12) defining a cylinder (14) extending along a longitudinal axis (16), and a first end position and a second end position. Between which a piston (18) arranged for reciprocating movement in the cylinder (14) along the longitudinal axis (16) and in the cylinder allows the inflow of fluid into the working chamber (20), The fluid inlet (22) for displacing the piston from the first end position to the second end position and the piston (18) are connected to a valve closing member (30), and the piston is at the first end position. When the valve closing member is in the open position and the piston is in the second end position, the valve closing means is provided with a connecting device (36) for sealing engagement with the valve seat (32). The connection means (36) is characterized by having a length which is variable in dependence on the fluid pressure in the working chamber (20), the valve assembly.

  (Item 2) The valve assembly according to item 1, characterized in that the connecting means (36) has an annular cross section, so that the connecting means define the internal chamber (38) in the axial direction.

  (Item 3) The valve assembly according to item 2, characterized in that the piston (18) has at least one through hole (40) cooperating with the internal chamber (38).

  (Item 4) The valve assembly according to any one of items 1 to 3, wherein the connecting means (36) is a flexible bellows.

  (Item 5) The valve assembly according to item 4, wherein the flexible bellows (36) is made of steel.

  (Item 6) The valve assembly according to any one of items 1 to 5, wherein the expansion suppressing means (46) connects the piston (18) to the valve closing member (30). .

  (Item 7) The valve assembly according to item 6, wherein the expansion suppressing means (46) passes through the internal chamber (38).

  (Item 8) The valve closing member (30) selectively connects an exhaust manifold (42) to an exhaust gas recirculation pipe (44) of the internal combustion engine (56). The valve assembly according to any one of the above.

  (Item 9) Use of the valve assembly according to any one of items 1 to 8 for operating an EGR valve in a diesel engine type vehicle.

  (Item 10) A plurality of valve assemblies (10a, 10b, 10a, 10b, 10a, 10b, connected in series and for controlling the amount of exhaust gas recirculation in a diesel-type vehicle according to any one of items 1 to 8 10c).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In the drawings, reference numeral 10 generally indicates a fluid operated valve assembly according to the present invention. The valve assembly 10 includes a housing 12 that defines a cylinder 14 that extends along a longitudinal axis 16. The piston 18 is arranged for reciprocal movement in the cylinder along the longitudinal axis 16. The piston 18 is arranged to be driven by a working fluid that is introduced into the working chamber 20 in the cylinder 14 via a fluid inlet 22, for example compressed air. In the embodiment shown in FIGS. 1 and 2, the fluid inlet 22 is provided in an end cap 24 that closes one axial end of the housing 12. Thus, the working chamber 20 is defined by the cylinder volume bounded by the end cap 24 and the piston 18.

  With the introduction of the working fluid, the piston 18 is displaced from a first end position where the piston is adjacent to the inlet 22 to a second end position remote from the inlet. In the first end position, the piston 18 is in sealing contact with the first sealing surface 26 of the cylinder 14. In the illustrated embodiment, it will be appreciated that the sealing surface may instead be provided on a separate insert inside the housing, but the first sealing surface bends inside the thinned wall region of the housing 12. Is advantageous. In the second end position, the piston 18 is in sealing contact with the second sealing surface 28, as shown in FIG. In the illustrated embodiment, the second sealing surface 28 takes the form of a shoulder provided by a reduced diameter section of the cylinder 14. Alternatively, the cylinder 14 may have a substantially uniform diameter along its length, but a second sealing surface is provided on the separate insert inside the housing.

  The displacement of the piston 18 from its first end position to its second end position is shown in FIG. 1 from the open position in which the valve closing member 30 is accommodated a certain axial distance within the housing 12. The valve closure member 30 is utilized to effect the displacement of the valve closure member 30 to a closed position where the valve closure member is in sealing engagement with the valve seat 32 near the axial end of the housing opposite the inlet 22. . Thus, at the second end position of the piston 18, the valve closing member 30 seals the end opening 34 at the end of the housing, while in its open position, the valve closing member has one or more peripheral directions in the housing 12. An end opening 34 in communication with the opening 35 is installed.

  To ensure that the valve closing member 30 is in sealing engagement with the valve seat 32 when the piston reaches its second end position without having to be exactly the same as the stroke of the closing member. In addition, the piston is connected to the valve closing member via variable length connecting means 36. In a preferred embodiment, and as illustrated in FIGS. 1 and 2, the connecting means is a flexible bellows, for example made from steel. Alternatively, the connecting means can be a nested arrangement with two or more relatively displaceable concentric tubes.

  The connecting means 36 may have an annular cross section, which is advantageously laser welded to the piston and valve closing means at their respective ends. Thus, in the axial direction, the connecting means 36 defines an internal chamber 38 that is closed at one end by the valve closing member 30. Due to the flexible nature of the connecting means, increasing the pressure in the inner chamber 38 tends to increase the length of the connecting means. In other words, the distance of the valve closing member 30 from the piston 18 increases.

  The pressure in the inner chamber 38 is advantageously determined by the inlet pressure, ie by the pressure in the working chamber 20. In such cases, as illustrated in FIGS. 1 and 2, the piston 18 is provided with one or more through holes 40, thereby allowing the internal chamber 38 to communicate with the working chamber 20.

  The operation of the fluid actuated valve assembly 10 described above will now be described with reference to FIGS. 1 and 2, in which the end opening 34 of the assembly communicates with the exhaust manifold 42 of the internal combustion engine, The opening 35 communicates with the exhaust gas recirculation pipe 44.

  If no pressurized fluid is supplied to the working chamber 20 of the cylinder 14, the back pressure in the exhaust manifold 42 acts on the underside of the valve closing member 30 and the piston 18 to displace the piston toward its first end position, Keep it there. Accordingly, the valve closing member 30 connects the exhaust manifold 42 to the recirculation pipe 44 by taking the open position.

  Compressed air is introduced into the working chamber 20 via the fluid inlet 22 when it is desired to prevent exhaust gas recirculation by closing the end openings 34. The compressed air acts inter alia on the piston 18 and rapidly moves the piston from its first end position to its second end position. Since the internal chamber 38 communicates with the working chamber 20, the compressed air also acts on the valve closing member 30, the fact that the piston and valve closing member are connected by a bellows 36, and the valve closing member 30 is connected to the end opening. Ensure displacement towards 34.

  Due to the flexible nature of the bellows 36, when the piston 18 reaches its second end position in contact with the second sealing surface 28, the air pressure in the inner chamber 38 until the valve closing member 30 is in sealing engagement with the valve seat 32. Expands the bellows 36. This is of course the case where the stroke of the piston is smaller than the stroke of the valve closing member. If the converse is true, when the valve closure member engages the valve seat 32, the air pressure acting on the piston 18 compresses the bellows and the piston can reach its second end position.

  In a typical application of a fluid operated valve assembly according to the present invention, the piston 18 may have a diameter of about 50 mm and a stroke of about 20 mm. Bellows 36 may have an unpressurized length of about 30 mm. In order to accommodate the difference in stroke length between the piston 18 and the valve closing member 30, it is usually sufficient if the bellows can change its length by about 0.3 mm. This relatively small change in the length of the bellows ensures that the strain on the bellows is correspondingly small, and so an effective long operating life of the bellows can be ensured.

  In the unlikely event that the piston 18 or valve closing member 30 becomes stuck in the cylinder, it is advantageous to be able to ensure that the bellows 36 are not subjected to unnecessary strain. In other words, in the unlikely event that the piston does not move halfway between its first and second end positions, the air pressure acting in the internal chamber 38 will somehow expand the bellows and cause the valve closure member to open the end opening. 34. Given such an expansion of the bellows, the bellows can be severely weakened.

  Accordingly, in a preferred embodiment of the present invention, as illustrated in FIG. 1, the valve assembly is provided with expansion restraining means 46 that connects the piston 18 to the valve closing member 30. Advantageously, the expansion restraining means 46 passes through the inner chamber 38. The expansion restraining means may be a substantially cylindrical configuration of a steel rod. The first end of the expansion restraining means has a plurality of radially extending projections 48 disposed in circumferentially extending cuts 50 in the piston through holes 40. In a corresponding manner, the second end of the expansion restraining means 46 has a plurality of radially extending projections 52 that are disposed in the notches 54 in the inner bore of the valve closure member 30. At least one of the notches 50, 54 has an axial extension that is greater than the axial extension of each protrusion, thereby limiting the amount that the bellows can expand.

  From the above, it is clear that the valve assembly according to the invention can be composed of very few components. Since the piston occupies only one of its end positions, it is not necessary to provide a seal between the piston and the cylinder during the piston displacement between the piston end positions. As such, there is no need for a piston ring and the valve assembly can withstand high temperatures. Thus, the valve assembly according to the present invention is excellent and suitable for use as an EGR valve for an internal combustion engine.

  A diesel engine 56 is schematically illustrated in FIG. 3, which is provided with a plurality of valve assemblies 10a, 10b, 10c of the present invention connected in series. The engine has an intake manifold 58, an exhaust manifold 42, and an exhaust gas recirculation (EGR) pipe 44. The area of the EGR pipe 44 that is open for gas flow is controlled by the valve assemblies 10a, 10b, and 10c. Advantageously, the first valve assembly 10a is provided with either 0% or 33% open areas, while the second valve assembly 10b is provided with either 0% or 67% open areas. The third valve assembly 10c in the closed position provides a 10% open area, and in the open position, provides a 100% open area.

Thus, when all valves are closed, there is no gas flow along the EGR pipe. When only the first valve assembly 10a is open, 10% open area is exposed. When both the first valve assembly and the third valve assembly are open, 33% open area is exposed. If only the second valve assembly and the third valve assembly are open, 67% open area is exposed. Eventually, when all valve assemblies are opened, 100% open area is exposed. In this manner, various degrees of opening of the EGR pipe can be achieved without having to resort to the use of variable displacement. Of course, the third valve assembly 10c can be of the type disclosed because only used to control the flow along a single passage, in Patent Document 1 (SE 9604287-4).

  The invention is not limited to the embodiments described above and illustrated in the drawings, but can be varied within the scope of the appended claims. For example, in certain embodiments, the piston may be provided with a guide ring that still allows leakage of working fluid between the piston and the cylinder wall.

(wrap up)
A fluid operated valve assembly (10) having a housing (12) defining a cylinder (14) extending along a longitudinal axis (16). The piston (18) is arranged for reciprocal movement in the cylinder (14) along the longitudinal axis (16) between the first end position and the second end position. The fluid inlet (22) allows fluid to enter the working chamber (20) in the cylinder, thereby displacing the piston from its first end position to its second end position. The assembly further includes connecting means (36) for connecting the piston (18) to the valve closing member (30), when the piston is in its first end position, the valve closing member is in the open position, and the piston is in its open position. When in the second end position, the valve closure member is in sealing engagement with the valve seat (32). In order to compensate for the stroke length difference between the piston (18) and the valve closing member (30), the connecting means (36) has a variable length depending on the fluid pressure in the working chamber (20).

The invention is described in further detail below for purposes of illustration and with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view of a fluid operated valve assembly according to the present invention in a first end position. FIG. 2 is a schematic cross-sectional view corresponding to FIG. 1 with the valve assembly in the second end position. And FIG. 3 is a schematic plan view of a diesel engine equipped with a plurality of valve assemblies according to the present invention.

Explanation of symbols

10 Valve assembly
12 Housing
14 cylinders
16 Longitudinal axis
18 piston
20 Working chamber
22 Fluid inlet
24 End cap
26, 28 Seal surface
30 Valve closing member
32 Valve seat
34 End opening
35 Peripheral opening
36 Connection means (bellows)
38 Internal chamber
40 Through hole
42 Exhaust manifold
44 Exhaust gas recirculation (EGR) pipe
46 Expansion suppression means
48, 52 Protrusion
50, 54 notch
56 Internal combustion engine
58 Intake manifold 58

Claims (10)

A fluid operated valve assembly (10) comprising:
A housing (12) defining a cylinder (14) extending along the longitudinal axis (16);
A piston (18) arranged for reciprocating movement in the cylinder (14) along the longitudinal axis (16) between a first end position and a second end position;
A fluid inlet (22) allowing fluid to flow into the working chamber (20) in the cylinder and displacing the piston from the first end position to the second end position;
When the piston (18) at one end of the connecting means is connected to the valve closing member (30) at the other end of the connecting means, and the piston seals and contacts the cylinder at the first end position, When the valve closing member is in the open position and the piston is in sealing contact with the cylinder at the second end position, the valve closing means comprises connection means (36) for sealing engagement with the valve seat (32). ,
A valve assembly characterized in that the connecting means (36) has a length that is variable depending on the fluid pressure in the working chamber (20). 2. A valve assembly according to claim 1, characterized in that the connecting means (36) has an annular cross section, so that the connecting means define the inner chamber (38) in the axial direction. The valve assembly according to claim 2, characterized in that the piston (18) has at least one through hole (40) cooperating with the internal chamber (38). 4. A valve assembly according to any one of claims 1 to 3, characterized in that the connecting means (36) is a flexible bellows. 5. A valve assembly according to claim 4, characterized in that the flexible bellows (36) are made of steel. 6. A valve assembly according to any one of claims 1 to 5, characterized in that expansion restraining means (46) connect the piston (18) to the valve closing member (30). The valve assembly according to claim 6, characterized in that the expansion restraining means (46) passes through the internal chamber (38). The valve closing member (30) selectively connects an exhaust manifold (42) to an exhaust gas recirculation pipe (44) of an internal combustion engine (56). The valve assembly according to any one of the above. For actuating the EGR valve in a diesel engine type vehicle, the valve Assen Bed Li according to any one of claims 1 to 8. A plurality of valve assemblies (10a, 10b, 10c ) according to any one of claims 1 to 8, connected in series and for controlling the amount of exhaust gas recirculation in a diesel-type vehicle. .

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